Chronic Gastrointestinal (GI) Blood Loss: The Primary Culprit
In men and postmenopausal women, the depletion of iron stores from chronic, subtle bleeding is the most frequent cause of iron deficiency. Unlike sudden, major bleeding events, this blood loss is often occult—meaning it's not visibly obvious—and occurs over a long period. Several GI conditions that increase with age are to blame:
- Peptic Ulcers: Long-term use of nonsteroidal anti-inflammatory drugs (NSAIDs) for conditions like arthritis, which is common in the elderly, is a significant risk factor for bleeding ulcers.
- Gastritis and Esophagitis: Inflammation of the stomach lining or esophagus can cause chronic irritation and low-grade blood loss.
- Polyps and Colon Cancer: As individuals age, the risk of developing polyps and colorectal cancer increases. These can bleed slowly over time, making GI evaluation crucial for any older adult with new-onset iron deficiency.
- Angiodysplasia: This condition involves fragile, dilated blood vessels in the GI tract that can cause intermittent bleeding.
The presence of other chronic health issues and the use of certain medications amplify the risk of GI bleeding. Medications like aspirin and anticoagulants, commonly used to prevent cardiovascular disease in older adults, significantly increase the risk of intestinal bleeding.
Impaired Iron Absorption: A Complex Factor
Beyond blood loss, the body's ability to absorb iron from food can be compromised in older age due to several physiological changes and underlying conditions.
- Helicobacter pylori Infection: This bacterial infection can cause chronic gastritis, which reduces stomach acid needed for iron absorption. H. pylori is particularly common in older populations.
- Atrophic Gastritis: This condition, where the stomach lining thins and loses its acid-producing cells, becomes more common with age. The resulting lack of stomach acid impairs iron absorption.
- Medications: The frequent use of proton pump inhibitors (PPIs) to treat acid reflux can significantly reduce stomach acid production, hindering the absorption of dietary iron.
- Celiac Disease: While often associated with younger adults, celiac disease can be newly diagnosed in older individuals, with malabsorption being a primary symptom.
Anemia of Chronic Inflammation (AI)
Anemia of chronic inflammation (AI), or anemia of chronic disease (ACD), is the most common form of anemia in the elderly. It's caused by inflammatory cytokines, which interfere with iron metabolism, leading to a condition known as functional iron deficiency. In this case, there may be sufficient iron stores in the body, but it cannot be properly released and used for red blood cell production.
Common inflammatory conditions that lead to AI in the elderly include:
- Chronic kidney disease (CKD)
- Heart failure
- Malignancies
- Autoimmune diseases like arthritis
- Chronic infections
In older adults, iron deficiency and AI frequently coexist, making diagnosis difficult. Lab tests can be misleading as inflammation elevates ferritin levels, potentially masking a coexisting iron deficiency.
Inadequate Dietary Intake and Nutritional Deficiencies
Although usually not the sole cause in industrialized nations, poor nutrition can contribute to or worsen iron deficiency in the elderly, especially when combined with other issues. Many older adults experience:
- Reduced Appetite: Factors like depression, decreased physical activity, and impaired senses of taste and smell can diminish appetite.
- Limited Dietary Variety: Strict diets or financial constraints may limit access to iron-rich foods like meat, which contains highly absorbable heme iron.
- Vitamin Deficiencies: Deficiencies in other vital nutrients, such as Vitamin B12 and folate, can contribute to anemia and are common in older adults.
Comparison of Major Causes of Iron Deficiency in the Elderly
| Cause | Description | Common Triggers/Risk Factors | Diagnosis Challenges in Elderly |
|---|---|---|---|
| Chronic GI Blood Loss | Slow, often occult, bleeding from the digestive tract. | NSAIDs, anticoagulants, aspirin, peptic ulcers, gastritis, colon polyps, cancers, angiodysplasia. | Patients are often asymptomatic, requiring endoscopy for detection. Bleeding may be intermittent. |
| Impaired Absorption | Inability to effectively absorb iron from food. | H. pylori infection, atrophic gastritis, proton pump inhibitors (PPIs), celiac disease. | Often presents as refractory to oral iron treatment. Lack of classic malabsorption symptoms can delay diagnosis. |
| Chronic Inflammation (AI) | Interference with iron metabolism due to inflammatory state. | Chronic kidney disease, heart failure, autoimmune disorders, malignancy. | Elevated ferritin levels due to inflammation can mask a coexisting iron deficiency. |
| Poor Dietary Intake | Insufficient iron consumption in the diet. | Reduced appetite, poverty, chewing difficulties, or limited food choices. | Rarely the sole cause in developed nations, but exacerbates other issues. |
Diagnosis and Management of Iron Deficiency in the Elderly
Diagnosing iron deficiency in older adults can be challenging due to multiple coexisting health issues and complex lab results.
- Initial Evaluation: A thorough medical history should include reviewing all medications and a discussion of symptoms, which may be non-specific (e.g., fatigue).
- Lab Tests: While a low hemoglobin level is indicative of anemia, specialized tests are needed for accurate diagnosis in the elderly. The serum transferrin receptor-ferritin index is considered more sensitive and specific than a single ferritin level, which can be elevated by inflammation even in iron deficiency.
- GI Evaluation: Endoscopic procedures (upper endoscopy and colonoscopy) are often warranted to investigate potential bleeding sources in the gastrointestinal tract, even without visible signs of blood. For difficult cases, capsule endoscopy can explore the small bowel.
- Treatment of Underlying Cause: Addressing the root cause is critical. This could involve managing chronic diseases, adjusting medication, or treating H. pylori infection. Iron supplementation, often intravenous due to poor oral tolerance or absorption, is used to replenish iron stores.
Conclusion
While iron deficiency is common among older adults, it is not a normal part of aging. The most common cause of iron deficiency in the elderly is chronic, low-level bleeding from the gastrointestinal tract, often stemming from ulcers, inflammation, or malignancy. This primary cause is complicated by other factors like impaired iron absorption due to stomach issues or medications, and the impact of inflammation from coexisting chronic diseases. A comprehensive diagnostic approach that carefully evaluates all potential causes, including a search for occult blood loss, is essential for correct diagnosis and effective treatment.
Frontiers in Pharmacology: Iron deficiency in the elderly population, revisited in the hepcidin era
